1. Technical Field
The present invention relates to methods and apparatuses for sensing boundaries between materials, and more particularly, to a sensing method and apparatus for detecting positions of boundaries between at least two layers of materials and detecting changes in the boundary positions.
2. Description of Related Art
The sensing of boundaries between materials represents a monitoring or detecting technique which is usually ignored by the disaster prevention industry nowadays, and its main cause lies in a lack of a simple, stable and effective technique for effectuating the sensing of boundaries between materials.
In Taiwan, plenty of bridge failures, casualties, and property loss are caused by typhoons and earthquakes each year. According to statistics released by Taiwan's Directorate General of Highways, there are currently 10491 bridges in Taiwan, and some of which are old and poorly maintained, thus posing a safety risk. Hence, it is necessary to install a safety monitoring system on every bridge to prevent casualties and property loss which might otherwise be caused by bridge collapses as a result of natural disasters.
However, the installation of a safety monitoring system on every bridge in Taiwan does pose many challenges, for example, whether the safety monitoring system is sufficiently stable, and whether its manufacturing cost is low enough to justify its wide application.
What the safety monitoring system monitors substantially includes abutment scour, abutment tilt, and bridge displacement. Among these, abutment scour monitoring is most demanding, because a sensing apparatus for use in abutment scour monitoring has to be directly installed on the river bed. However, in hazardous waters, for example, turbulent waters, and rivers with floating wood, rocks, or muddy water, a conventional abutment scour sensor is susceptible to ambient interference, and is even likely to be hit by foreign bodies and thus get damaged. As a result, performing abutment scour monitoring persistently in hazardous waters for a long period of time is an important but demanding task. In view of this, it is imperative to provide a kind of low-cost sensing apparatuses to be extensively deployed in an adverse environment for long-term surveillance with a view to enhancing bridge safety. To this end, a material boundary sensing apparatus and method are required.